Proteorhodospin-bearing bacteria in Antarctic sea ice

Proteorhodopsins (PRs) are widespread bacterial integral membrane proteins that function as light-drivenproton pumps. Antarctic sea ice supports a complex community of autotrophic algae, heterotrophic bacteria,viruses, and protists that are an important food source for higher trophic levels in ice-c...

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Bibliographic Details
Published in:Applied and Environmental Microbiology
Main Authors: Koh, EY, Atamna-Ismaeel, N, Martin, AR, Cowie, ROM, Beja, O, Davy, SK, Maas, EW, Ryan, KG
Format: Article in Journal/Newspaper
Language:English
Published: Amer Soc Microbiology 2010
Subjects:
Biological Sciences
Microbiology
Microbial Ecology
Antarctic
Ross Sea
Antarc*
Sea ice
Online Access:http://aem.asm.org/cgi/content/abstract/76/17/5918
https://doi.org/10.1128/AEM.00562-10
http://www.ncbi.nlm.nih.gov/pubmed/20601510
http://ecite.utas.edu.au/68331
Description
Summary:Proteorhodopsins (PRs) are widespread bacterial integral membrane proteins that function as light-drivenproton pumps. Antarctic sea ice supports a complex community of autotrophic algae, heterotrophic bacteria,viruses, and protists that are an important food source for higher trophic levels in ice-covered regions of theSouthern Ocean. Here, we present the first report of PR-bearing bacteria, both dormant and active, inAntarctic sea ice from a series of sites in the Ross Sea using gene-specific primers. Positive PR sequences weregenerated from genomic DNA at all depths in sea ice, and these sequences aligned with the classes Alphaproteobacteria,Gammaproteobacteria, and Flavobacteria. The sequences showed some similarity to previouslyreported PR sequences, although most of the sequences were generally distinct. Positive PR sequences werealso observed from cDNA reverse transcribed from RNA isolated from sea ice samples. This finding indicatesthat these sequences were generated from metabolically active cells and suggests that the PR gene is functionalwithin sea ice. Both blue-absorbing and green-absorbing forms of PRs were detected, and only a limitednumber of blue-absorbing forms were found and were in the midsection of the sea ice profile in this study.Questions still remain regarding the proteins ecological functions, and ultimately, field experiments will beneeded to establish the ecological and functional role of PRs in the sea ice ecosystem.

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